1. Field of the Invention
The present invention relates to a printing system for requesting processing and printing with respect to a processor and a printer, which are connected to each other through a network to make the processor and the printer perform processing and printing of data to be printed and a method therefor.
2. Description of the Related Art
When print data is acquired from a data server device connected to a network and is printed, a place of the print data, a printer of a print destination and an application capable of converting the print data into a format suitable for the printer are required.
That is, as the necessary minimum number of configurations for printing, a client device for issuing a print request of print data by an operation of a user, a data server device for holding the print data, a printer for doing printing and further the application for making the conversion described above are required.
As a matter of course, the application for conversion and the print data must together reside in a node such as a client device in order to convert the print data into the format suitable for the printer.
When it is known whether the node in which the application resides is a client device or a printer, the following two methods for this conversion can be given.
That is, a push type method (for example, lpr of RFC1179) in which an application resides in a client device and print data is converted in the client device and the converted print data is sent to a printer can be given as a first method. A pull type method (for example, ipp of IRTF) in which an application resides in a printer and conversion processing is performed with respect to print data brought by the printer also can be given as a second method.
First, the push type method will be described with reference to FIG. 1.
FIG. 1 is a diagram showing push type processing for converting print data.
As shown in FIG. 1, in the push type method, a client device first requests print data with respect to a data server device (FIG. 1 (1)) and acquires the print data from the data server device (FIG. 1(2)).
Next, a client performs conversion processing using an application for conversion processing and converts the print data into a format suitable for a printer.
Further, the client sends the converted print data to the printer and does printing (FIG. 1(3)).
Next, the pull type method will be described with reference to FIG. 2.
FIG. 2 is a diagram showing pull type processing for converting print data.
Unlike the push type method, in the pull type method shown in FIG. 2, a client device first requests a printer of printing of print data (FIG. 2(1)).
Then, the printer requests a data server device of the print data (FIG. 2(2)) and acquires the print data (FIG. 2(3)).
Further, the printer converts the print data using an application provided them and does printing.
In order to use the push type method, the client device needs to know that which of the data server device the print data resides (a place of the print data), that which printer performs printing (a print destination) and that an application capable of conversion resides in a client.
Also, it is necessary to acquire the print data from the data server device and to perform conversion processing, so that a processing load of the client device is large and during these processing, many machine powers can be spent in other processing.
Also, in the case of performing plural conversion processing, it is necessary to provide all the applications for performing these conversion processing in the client device.
In the case of using the pull type method, the client device needs to know a place of the print data and a print destination, but does not need to know a place where an application resides. Also, the printer needs to recognize that an application for conversion is provided therein.
Also, as a matter of course, the print data cannot be printed unless an application is provided in the printer.
As became evident from the above description, even in the case of using the push type or the case of using the pull type, the application for conversion processing must be provided in the client device or the printer.
A system capable of converting and printing print data without providing the application for conversion processing in the client device or the printer will be described below with reference to FIG. 3.
FIG. 3 is a diagram showing a method (single stage conversion method) for doing printing using a processor.
In the single stage conversion method shown in FIG. 3, a printer first acquires print data as with the pull type method (FIG. 3(1) to FIG. 3(3)).
Next, when it is decided that the print data acquired by the printer is described in a format incapable of interpretation, it is searched whether there is a processor in which an application for performing conversion processing is provided, and the print data is sent to the processor found as a result of the search, and the conversion is requested (FIG. 3(4)).
The processor receives the print data and performs the conversion processing and when returning the converted print data to the printer (FIG. 3(5)), the printer prints the converted print data.
According to the single stage conversion method shown in FIG. 3, it is unnecessary to provide the application for conversion processing in a client or the printer and also, the conversion processing can be performed with respect to the print data even when a client device does not know the presence of the application.
Therefore, the client device can print the print data as long as the client device knows a place of the print data and a print destination.
For example, a method in which a network printer receives a print request from a client device and requests sending of a document from a file server and prints the document processed by a conversion processing server in a network to which the client device, the file server, the conversion processing server and the network printer are connected is disclosed in JP-A-10-207657.
However, in the single stage conversion method shown in FIG. 3, all the conversion processing of the print data read from the data server device must be processed and printed by one processor, so that conversion processing which is not provided in the processor cannot be performed as a matter of course.
Also, for example, in the case that the printer of FIG. 3 can print the print data with a format C and the data server device holds the print data with a format A, even when there is no application for converting the format A into the format C, for example, by converting the print data with the format A into an intermediate format B and further converting the format B into the format C, the print data suitable for the printer can be generated.
However, according to the single stage conversion method shown in FIG. 3, multistage conversion processing for converting the print data into the intermediate format once and further converting it into the final format in this manner cannot be performed.
Therefore, many kinds of applications must be provided in the processor, and large effort and cost are required in order to create such an application for conversion processing.
For example, when a function of N-up for combining plural sheets of print data into one sheet to do printing wants to be performed by a printer without such a function, first, it is necessary to perform processing of the N-up with respect to the print data and further convert the processed print data into formats such as PS, PCL or PDL suitable for the printer.
Such multistage processing cannot be implemented by the single stage conversion method shown in FIG. 3, and large effort and cost are required in order to create a program in which the N-up function is integrated with conversion processing into the formats such as PS.
Also, for example, a user can operate the client device every one conversion to perform the multistage processing, but such operations put a large burden on the user.
When the multistage processing includes image conversion involving irreversible deformation such as compression, color conversion, scaling, noise rejection, or encryption, it is necessary to perform conversion processing in such order that information loss from the original print data is suppressed as low as possible. This is a problem.
Furthermore, when a necessary application for conversion processing is not present in the network, optimum conversion order can not be determined because of avoiding this processing conversion. This is also a problem.